Greenhouse gases are gaseous components which absorb the infrared radiation emitted by the surface of the earth, thus contributing to the greenhouse effect. The increase in their concentration in the atmosphere is one of the factors causing global warming.
The production of the chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) used in refrigeration and air conditioning systems has thus been successively regulated by the Montreal protocol and then the Kyoto protocol. There exists a need to develop new molecules which are as effective and which in particular exhibit the smallest possible global warming potential. This is the case with hydrofluoroolefins and in particular HFO-1234yf, which is a particularly useful compound.
It is known to produce hydrofluoroolefins or hydrofluorocarbons by fluorination of hydrochloroolefins or of hydrochlorocarbons in particular. This fluorination is generally a catalytic fluorination using hydrofluoric acid as fluorinating agent.
The fluorination reaction generally has to be carried out at a high temperature (more than 300° C.) in the gas phase, in the presence of a supported or bulk solid catalyst.
It is known to provide cofeeding with an oxidizing agent, in particular air, or optionally chlorine, in order to preserve the lifetime of the catalyst and to limit the deposition of coke at its surface during the reaction stage.
The document U.S. Pat. No. 8,614,361 describes a process for the manufacture of HFO-1234yf by reacting HCFO-1233xf with HF in the presence of a high oxygen content.
The document U.S. Pat. No. 8,618,338 describes a process for the manufacture of fluoroolefin in two stages, in particular a first stage of reaction in the liquid phase starting from 1,1,2,3-tetrachloropropene (HCO-1230xa), in order to obtain the intermediate HCFO-1233xf, and a second stage of reaction in the gas phase starting from HCFO-1233xf, in order to obtain HFO-1234yf.
The document WO 2013/088195 teaches a process for the manufacture of HFO-1234yf in two stages, a first stage of fluorination in the gas phase of 1,1,1,2,3-pentachloropropane (HCC-240db) and/or of 1,1,2,2,3-pentachloropropane (HCC-240aa), in order to obtain the intermediate HCFO-1233xf, and then a second stage of reaction in the gas phase starting from HCFO-1233xf, in order to obtain HFO-1234yf.
The documents WO 2012/098421 and WO 2012/098422 teach the activation and the regeneration of fluorination catalysts.
The document WO 2013/182816 describes a chemical reaction process for the alternating implementation of a phase of catalytic reaction and of a phase of regeneration of catalyst in a reactor.
There still exists a need to improve the processes for the manufacture of HFO-1234 compounds, such as HFO-1234yf, and in particular to produce these compounds with a high yield and with a high degree of purity.